An electrode for a rechargeable lithium battery is produced by coating an active material composition on a current collector and drying it to form an active mass layer on the current collector. The active material composition includes an active material, a binder, optionally a conductive binder, and an organic solvent.
The active mass layer should be firmly maintained without separation from the current collector during initial charging in order to guarantee high capacity and good cycle life characteristics. Good adhesion between the active mass layer and the current collector depends on the choice of suitable binders. The binder is required to render a physical binding strength to the electrode in only a small amount, which leads to provision of a positive electrode with a high energy density. The binder must also be unreactive with the electrolyte solution and must maintain a stable form within the battery operating temperature range.
Binders satisfying such requirements include aqueous binders such as styrene rubber and carboxymethyl cellulose. However, the aqueous binders generate gas caused by moisture in the electrode, and carboxymethyl cellulose decomposes or forms thin layers on the negative electrode, thereby expanding the volume of the battery.